Inhibition of lipoxygenase and prostaglandin endoperoxide synthase by anacardic acids

C22:1 omega 5-anacardic acid was found to be a good inhibitor of both potato lipoxygenase and ovine prostaglandin endoperoxide synthase with approximate IC50's of 6 and 27 microM, respectively. Very similar inhibition was seen with the crude exudate, rich in omega 5-anacardic acids, from glandular trichomes of an arthropod-resistant strain of geranium, Pelargonium xhortorum. The saturated anacardic acid (C22:0 sat), abundant in the trichome exudate of susceptible strains, was nearly as inhibitory toward both prostaglandin endoperoxide synthase and lipoxygenase as the omega 5-unsaturated compound. However, the dimethyl derivative of C22:1 omega 5-anacardic acid was a poor inhibitor of prostaglandin endoperoxide synthase and caused only moderate (32%) inhibition of lipoxygenase even at 135 microM. The possible role of prostaglandin endoperoxide synthase and lipoxygenase inhibition in the enhanced pest resistance of geraniums which produce the omega 5-AnAs is discussed.     

2,4-Diacetylphloroglucinol suppresses zoosporogenesis and impairs motility of Peronosporomycete zoospores

2,4-Diacetylphloroglucinol (DAPG) produced by Pseudomonas fluorescens, shows toxicity to many microorganisms including fungi, bacteria, and peronosporomycetes. Zoosporogenesis and motility of zoospores are critical for a complete disease cycle and pathogenicity of the peronosporomycete phytopathogens. The aim of this study was to test the effects of DAPG and its derivatives on zoosporogenesis and motility of zoospores of a downy mildew pathogen, Plasmopara viticola, and a damping-off pathogen, Aphanomyces cochlioides. In both cases, DAPG inhibited zoosporogenesis (5 μg/ml) and the motility of zoospores (10 μg/ml) in a dose-dependent manner. Generally, zoospores became immotile shortly after exposure to DAPG followed by lysis. However, a fraction of DAPG treated A. cochlioides zoospores formed round cystospores instead of lysis and then germinated with excessively-branched germ tubes. All derivatives of DAPG had similar inhibitory activities but at varying doses. Among them, 2,4-dipropylphloroglucinol exerted the highest inhibitory activity against both zoosporogenesis and motility of zoospores. This revealed that the degree of hydrogen atoms substitution in the benzene ring by acyl groups and the length of substituted acyl groups were related to the level of bioactivity. This is the first report of inhibitory activities of DAPG and its derivatives against zoosporogenesis and motility of zoospores of two important peronosporomycete phytopathogens.     

Secondary metabolites from nonhost plants affect the motility and viability of phytopathogenic Aphanomyces cochlioides zoospores

The motile zoospores of the damping-off pathogen Aphanomyces cochlioides aggregate on host plants (e.g., sugar beet, spinach) guided by the host-specific plant signal cochliophilin A before infection. To assess the potential role of secondary metabolites in nonhost resistance, acetone extracts of 200 nonhost traditional medicinal plants from Chinese and Bangladeshi origins were tested for the motility behaviour of A. cochlioides zoospores using a particle bioassay method. Nearly one third of the tested plant extracts exhibited diverse deleterious activities such as repellent, stimulant, motility halting and lysis against A. cochlioides zoospores. Among these active plants, an extract of the Chinese medicinal plant Dalbergia odorifera displayed potent repellent activity toward zoospores. Chromatographic separation of D. odorifera constituents revealed that the repellent activity was regulated by the cumulative effect of three motility-affecting isoflavonoids, viz. (+/-)-medicarpin (repellent at 150 microg/ml), (-)-claussequinone (stimulant at 100 microg/ml) and formononetin (stimulant and attractant at 50 microg/ml). A mixture (1:1:1, w/w/w) of these three compounds exhibited only repellent activity toward zoospores at a concentration lower than 50 microg/ml. These results suggest that nonhost plants might possess potential bioactive secondary metabolites to ward off zoosporic phytopathogens.     

Depsidones and other constituents from Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides with potent inhibitory effect on motility of zoospores of grapevine pathogen Plasmopara viticola

In our search for secondary metabolites regulating the motility behavior of zoospores of the grapevine downy mildew pathogen Plasmopara viticola, we found that extracts from an endophytic fungus Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides remarkably impaired motility of zoospores followed by lysis. The active principles in the extracts were isolated and identified as two new compounds, namely excelsional (1a) and 9-hydroxyphomopsidin (2a), together with excelsione (1b), phomopsidin (2b), alternariol (3a), alternariol-5-O-methyl ether (3b), the hitherto undescribed 5′-hydroxyalternariol (3c), altenusin (4) from the fungus, xanthochymol (5) and 1,5-dihydroxy-3-methoxyxanthone (mesuaxanthone, 6) from the plant. Bioassays revealed that compounds 1a/b, 2a/b, and 3a–6 displayed motility inhibition and lytic activities against zoospores of the grapevine downy mildew pathogen P. viticola in a dose- and time-dependent manner from 1 to 10 μg/mL. Their structures were elucidated by extensive spectroscopic analyses including 2D NMR techniques. This is the first report of an endophyte and its natural products from E. calophylloides and the first isolation of compounds 5 and 6 from this plant.     

Lipid profiling of the soybean pathogen Phytophthora sojae using Fatty Acid Methyl Esters (FAMEs)

Phytophthora sojae is a destructive soilborne pathogen of soybean, but currently there is no rapid or commercially available testing for its infestation level in soil. For growers, such information would greatly improve their ability to make management decisions to minimize disease damage to soybean crops. Fatty acid profiling of P. sojae holds potential for determining the prevalence of this pathogen in soil. In this study, the Fatty Acid Methyl Ester (FAME) profile of P. sojae was determined in pure culture, and the profile was subsequently evaluated for its potential use in detecting the pathogen in soil. The predominant fatty acids in the FAME profile of P. sojae are the unsaturated 18C fatty acids (18:1ω9 and 18:2ω6) followed by the saturated and unsaturated 16C fatty acids (16:0 and 16:1ω7). FAME analysis of P. sojae zoospores showed two additional long-chain saturated fatty acids (20:0 and 22:0) that were not detected in the mycelium of this organism. Addition of a known number of zoospores of P. sojae to soil demonstrated that fatty acids such as 18:1ω9, 18:2ω6, 20:1ω9, 20:4ω6, and 22:1ω9 could be detected and quantified against the background levels of fatty acids present in soil. These results show the potential for using selected FAMEs of P. sojae as a marker for detecting this pathogen in soybean fields.     

Nicotinamide and structurally related compounds show halting activity against zoospores of the phytopathogenic fungus Aphanomyces cochlioides

In a survey of plant secondary metabolites regulating the behavior of phytopathogenic Aphanomyces cochlioides zoospores, we found that leaf extracts of Amaranthus gangeticus and cotyledon extracts of pea (Pisum sativum) remarkably halted the motility of zoospores. Bioassay-directed fractionation of A. gangeticus and pea constituents revealed that the halting activity was dependent on a single chemical factor (halting factor). The active principle was identified as nicotinamide (1) by comparing its biological activity and spectroscopic properties with those of the authentic compound. Nicotinamide (1) showed potent halting activity toward the zoospores of A. cochlioides and A. euteiches, but it exhibited very less activity against other Oomycetes, Pythium aphanidermatum and Phytophthora infestans zoospores. Interestingly, the zoospores halted by nicotinamide (1) encysted within 10-15 min and then the resulting cystospores regenerated zoospores instead of germination. Nicotinamide (1) and related compounds were subjected to the halting activity bioassay to elucidate the structure-activity relationships. These bioassays revealed that part structures of (A) the aromatic ring containing at least one nitrogen atom, (B) carbonyl-like group adjacent to the aromatic ring and (C) hydrogen atoms on the amide group are responsible for the strong activity. So far, this is the first report of halting activity of nicotinamide (1) against fungal zoospores.     

Phytophthora nicotianae transformants lacking dynein light chain 1 produce non-flagellate zoospores

Biflagellate zoospores of the highly destructive plant pathogens in the genus Phytophthora are responsible for the initiation of infection of host plants. Zoospore motility is a critical component of the infection process because it allows zoospores to actively target suitable infection sites on potential hosts. Flagellar assembly and function in eukaryotes depends on a number of dynein-based molecular motors that facilitate retrograde intraflagellar transport and sliding of adjacent microtubule doublets in the flagellar axonemes. Dynein light chain 1 (DLC1) is one of a number of proteins in the dynein outer arm multiprotein complex. It is a 22 kDa leucine-rich repeat protein that binds to the catalytic motor domain of the dynein γ heavy chain. We report the cloning and characterization of DLC1 homologues in Phytophthora cinnamomi and Phytophthora nicotianae (PcDLC1 and PnDLC1). PcDLC1 and PnDLC1 are single copy genes that are more highly expressed in sporulating hyphae than in vegetative hyphae, zoospores or germinated cysts. Polyclonal antibodies raised against PnDLC1 locallized PnDLC1 along the length of the flagella of P. nicotianae zoospores. RNAi-mediated silencing of PnDLC1 expression yielded transformants that released non-flagellate, non-motile zoospores from their sporangia. Our observations indicate that zoospore motility is not required for zoospore release from P. nicotianae sporangia or for breakage of the evanescent vesicle into which zoospores are initially discharged.     

Protein kinase C is likely to be involved in zoosporogenesis and maintenance of flagellar motility in the peronosporomycete zoospores

The motility of zoospores is critical in the disease cycles of Peronosporomycetes that cause devastating diseases in plants, fishes, vertebrates, and microbes. In the course of screening for secondary metabolites, we found that ethyl acetate extracts of a marine Streptomyces sp. strain B5136 rapidly impaired the motility of zoospores of the grapevine downy mildew pathogen Plasmopara viticola at 0.1 μg/ml. The active principle in the extracts was identified as staurosporine, a known broad-spectrum inhibitor of protein kinases, including protein kinase C (PKC). In the presence of staurosporine (2 nM), zoospores moved very slowly in their axis or spun in tight circles, instead of displaying straight swimming in a helical fashion. Compounds such as K-252a, K-252b, and K-252c structurally related to staurosporine also impaired the motility of zoospores in a similar manner but at varying doses. Among the 22 known kinase inhibitors tested, the PKC inhibitor chelerythrine was the most potent to arrest the motility of zoospores at concentrations starting from 5 nM. Inhibitors that targeted kinase pathways other than PKC pathways did not practically show any activity in impairing zoospore motility. Interestingly, both staurosporine (5 nM) and chelerythrine (10 nM) also inhibited the release of zoospores from the P. viticola sporangia in a dose-dependent manner. In addition, staurosporine completely suppressed downy mildew disease in grapevine leaves at 2 μM, suggesting the potential of small-molecule PKC inhibitors for the control of peronosporomycete phytopathogens. Taken together, these results suggest that PKC is likely to be a key signaling mediator associated with zoosporogenesis and the maintenance of flagellar motility in peronosporomycete zoospores.     

Monoclonal antibodies to cell surface components of zoospores and cysts of the fungusPythium aphanidermatum reveal species-specific antigens

A panel of monoclonal antibodies (MAbs) designated PA1 to PA8 has been raised against cell surface components of zoospores and cysts of the pathogenic fungusPythium aphanidermatum. The antibodies were selected on the basis of binding assays using indirect immunofluorescence. Four binding patterns were observed: PA1 labeled the entire zoospore surface including both flagella, PA2 binding was restricted to the anterior flagellum, PA3–PA6 bound to the adhesive cell coat secreted by zoospores during encystment, and PA7 and PA8 labeled zoospores and the cyst cell wall. Electron microscopic immunogold labeling of zoospores showed that PA2 bound to the mastigonemes on the anterior flagellum. The MAbs were tested for binding to zoospores and cysts of several isolates ofP. aphanidermatum, and to zoospores and cysts of several species ofPythium, Phystophthora, Aphanomyces, andSaprolegnia. The results showed that the antigens recognized by MAbs PA1–PA6 were restricted toP. aphanidermatum, whereas those recognized by PA7 and PA8 occurred on all species tested.     

6-Hydroxykynurenic acid and kynurenic acid differently antagonise AMPA and NMDA receptors in hippocampal neurones

6-Hydroxykynurenic acid (6-HKA), a derivative of kynurenic acid (KYNA) extracted from Ginkgo biloba leaves, was tested for its putative glutamate receptor (GluR) antagonism in comparison to the scaffold substance. The patch-clamp method together with fast-application techniques were used to estimate inhibition by 6-HKA and KYNA of agonist binding at NMDA and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (NMDARs and AMPARs) of CA1 pyramidal neurones. 6-Hydroxykynurenic acid proved to be a low-affinity antagonist. When comparing with KYNA, 6-HKA was less potent at NMDARs (IC(50) = 136 versus 59 microM), but showed a higher affinity to AMPARs (K(B) = 22 versus 172 microM). The replacement of 6-HKA and KYNA by glutamate was investigated on outside-out patches. Both antagonists competitively inhibited AMPAR responses and displayed fast unbinding kinetics, but the derivative was significantly slower displaced than KYNA (tau = 1.63 versus 1.22 ms). Our findings demonstrate that 6-hydroxylation considerably changes the pharmacological profile of KYNA. Among the 6-derivatives of KYNA, 6-HKA shows the highest affinity to AMPARS: Despite its relatively low lipophily, these properties might be of clinical relevance under conditions that compromise the integrity of the blood-brain barrier. Furthermore, 6-HKA should be a useful tool to analyse glutamate-mediated synaptic responses.     

Biochemical, genetic, and zoosporicidal properties of cyclic lipopeptide surfactants produced by Pseudomonas fluorescens

Zoospores play an important role in the infection of plant and animal hosts by oomycetes and other zoosporic fungi. In this study, six fluorescent Pseudomonas isolates with zoosporicidal activities were obtained from the wheat rhizosphere. Zoospores of multiple oomycetes, including Pythium species, Albugo candida, and Phytophthora infestans, were rendered immotile within 30 s of exposure to cell suspensions or cell culture supernatants of the six isolates, and subsequent lysis occurred within 60 s. The representative strain SS101, identified as Pseudomonas fluorescens biovar II, reduced the surface tension of water from 73 to 30 mN m-1. The application of cell suspensions of strain SS101 to soil or hyacinth bulbs provided significant protection against root rot caused by Pythium intermedium. Five Tn5 mutants of strain SS101lacked the abilities to reduce the surface tension of water and to cause lysis of zoospores. Genetic characterization of two surfactant-deficient mutants showed that the transposons had integrated into condensation domains of peptide synthetases. A partially purified extract from strain SS101 reduced the surface tension of water to 30 mN m-1 and reached the critical micelle concentration at 25 micrograms ml-1. Reverse-phase high-performance liquid chromatography yielded eight different fractions, five of which had surface activity and caused lysis of zoospores. Mass spectrometry and nuclear magnetic resonance analyses allowed the identification of the main constituent as a cyclic lipopeptide (1,139 Da) containing nine amino acids and a 10-carbon hydroxy fatty acid. The other four zoosporicidal fractions were closely related to the main constituent, with molecular massesranging from 1,111 to 1,169 Da.     

Mode of antagonism of a biocontrol bacterium Lysobacter sp. SB-K88 toward a damping-off pathogen Aphanomyces cochlioides

The biocontrol bacterium Lysobacter sp. SB-K88 suppresses damping-off disease in sugar beet and spinach caused by Aphanomyces cochlioides and Pythium sp. through characteristic plant colonization and antibiosis against the pathogens. This study aimed to unravel further details on mode of antagonism of SB-K88 against a damping-off pathogen A. cochlioides AC-5. The SB-K88 substantially inhibited growth and decomposed AC-5 mycelia and suppressed the release of zoospores from the hyphae. The excised root tips of sugar beet seedlings from seeds previously inoculated with SB-K88 were less attractive to AC-5 zoospores. Although aerial growth was not affected, however, root hairs of SB-K88 inoculated sugar beet seedlings were remarkably shorter and thicker than those of uninoculated control. When exposed to zoospores, the SB-K88 inhibited motility of zoospores and/or caused lysis, and then aggregated around the dead cystospores or lysed residues within 3–6 h likely to be micro-predatory behavior to a eukaryotic organism. Confocal laser scanning microscopic analysis revealed that number of lipid bodies and activities of mitochondria were markedly increased in the affected hyphae compared with control hyphae as visualized by established vital stains. Taken together, these results suggest that Lysobacter sp. SB-K88 suppresses damping-off diseases through exerting multifaceted antagonistic effects against the peronosporomycetes.     

Studies on Antagonistic Effects of Trichoderma Isolates Against Phytophthora cactorum

Bioassays were used to demonstrate the antibiotic effect of Trichoderma isolates on P. cactorum. When both fungi were grown on benomyl-containing PDA medium, the mycelial growth of Trichoderma was suppressed. However, the production of antibiotics by this fungus remained active, leading to inhibition of the mycelial growth of P. cactorum. The antibiotic effect of Trichoderma on zoospores and cysts was tested on a PDA substrate precultured with Trichoderma on cellophane sheets. On the substrate of some Trichoderma isolates, lysis of zoospores, formation of extracellular vesicles, and hypertrophy of the water expulsion vesicle did occur, both resulting in the death of the zoospores. Conidial suspensions of Trichoderma isolates also induced zoospore lysis. It is presumed that membrane-active peptide antibiotics (peptaibols) are involved in zoospore lysis. The peptaibol paracelsin caused lysins of zoospores at a concentration of 2.5 × 10^?4 M. The effect on cysts depended on the Trichoderma isolate tested and the age of Trichoderma preculture. Old cultures (after beginning of sporulation) affected cysts more severely than young cultures (before sporulation) which usually were not lethal to the cysts but induced preferably microsporangium formation, inhibition of cyst germination, and retardation of germ tube growth.     

Heterocyclic rimantadine analogues with antiviral activity

2-(1-Adamantyl)pyrrolidines 6, 7, 2-(1-adamantyl)piperidines 10, 12a–c, 15a,b and 2-(1-adamantyl)hexahydroazepines 19, 21, 22 were synthesized and tested for their antiviral activity against influenza A, B viruses and the human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2). The synthetic procedure followed for the preparation of the parent piperidine 10 represents a general method for the synthesis of 2-alkyl- or cycloalkyl-substituted piperidine alkaloids. Parent aminoadamantanes 6, 10 and 19 contain the 1-aminoethyl pharmacophore group of rimantadine drug 2, extended into a saturated nitrogen heterocycle: pyrrolidine, piperidine and hexahydroazepine, respectively. The ring size effect in anti-influenza A activity was investigated. Rimantadine analogues 6 and 10 were, respectively, 6- and 4-fold more active than the drug Rimantadine 2, whereas the hexahydroazepine derivative 19 was inactive. Thus, enlargement from a 5-(pyrrolidine)- or 6-(piperidine)- to a 7-(hexahydroazepine)- membered heterocyclic ring dramatically reduced the anti-influenza virus A activity. Substitution of piperidine 10 with a dialkyaminoethyl group led to the active compounds 15a and 15b: compound 15a was active against influenza A virus whereas both 15a and 15b were active against HIV-1.     

Novel carboranyl amino acids and peptides: reagents for antibody modification and subsequent neutron-capture studies.

A new alpha-amino acid derivative incorporating the 1,2-dicarba-closo- dodecarborane(12) cage, namely 5-(2-methyl-1,2-dicarba-closo-dodecarborane(12)-1-yl)- 2-aminopentanoic acid (2), was synthesized by the alkylation of the benzophenone Schiff's base of glycine methyl ester with 3-(2-methyl-1,2-dicarba-closo-dodecaborane(12)-1-yl)pr opyl iodide (8). This amino acid was employed in the synthesis of peptide derivatives such as 19-21 using solid-phase Merrifield methods. Dipeptide 19 was converted to a water-soluble ionic derivative by the pyrrolidine-mediated carborane cage degradation reaction followed by cation exchange to afford sodium salt 22. Dansylation of 22 with dansyl chloride yielded fluorescence-labeled dipeptide 23. Undecapeptide 21 was dansylated while still anchored to the Merrifield resin. Following its cleavage from the resin with hydrogen fluoride, product 25 was acetylated to block the free amino group on the lysine residue and then converted to water-soluble derivative 27. Trial conjugations of dipeptide 23 and undecapeptide 27 to T84.66, an anti-CEA antibody, were carried out by means of carboxyl activation with N-hydroxysulfosuccinimide and N,N-diisopropylcarbodiimide. Studies of the chemical syntheses of these and other peptide derivatives and the conjugation of 23 and 27 to the antibody are described.     

Host-specific plant signal and G-protein activator, mastoparan, trigger differentiation of zoospores of the phytopathogenic oomycete Aphanomyces cochlioides

We found that the gradient of a host-specific attractant, cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone) isolated from the roots of spinach triggered encystment followed by germination of zoospores of Aphanomyces cochlioidesat a concentration less than micromolar order. This compound did not affect the growth and reproduction of this phytopathogen up to 10^–6 M concentration in the culture medium. We also observed that mastoparan, an activator of heterotrimeric G-protein could inhibit the motility of zoospores and then strikingly effect encystment followed by 60–80% germination of cysts. Concomitant application of cochliophilin A and mastoparan showed stronger encystment followed by 100% germination of cysts. In addition, we have observed that chemicals interfering with phospholipase C activity (neomycin) and Ca²⁺ influx/release (EGTA and loperamide) suppress cochliophilin A or mastoparan induced encystment and germination. These results suggest that G-protein mediated signal transduction mechanism may be involved in the differentiation of the A. cochlioides zoospores. This is the first report on the differentiation of oomycete zoospores initiated by a host-specific plant signal or a G-protein activator.     

Interleukin-2- and mitogen-activated NK-like killer cells from highly purified human peripheral blood T cell (CD3+ N901-) cultures

In this study, highly purified (HP) CD3-positive N901-negative T lymphocytes could be induced to become natural killer (NK)-like in culture in the presence of recombinant interleukin-2 (rIL-2) and phytohemagglutinin (PHA). Thus, purified CD3+ N901- T cells from fresh human peripheral blood were obtained by negative selection using an indirect panning technique. To ensure that T lymphocyte fractions were completely devoid of any detectable NK cells, two additional purification procedures were employed: incubation of post-pan T cells with the NK-cytotoxic lysomotropic agent L-leucinemethylester, and complement-mediated lysis using the NK cell specific NKH1a monoclonal antibody. Purity of CD3+ N901- cells could be confirmed by surface marker analysis, whereby two NK-associated antigens, N901 and H-25, were undetectable, while 94 +/- 1% of cells expressed the CD3 (Leu-4) antigen. On functional analysis, fresh HP CD3+ N901- cells exhibited no cytotoxic activity against the standard NK target K562. When HP NK-depleted T lymphocytes were cultured for 7 days in the presence of rIL-2 (100 U/ml), neither surface antigen expression nor cytotoxic activity against K562 changed significantly. However, significant cytotoxicity against K562 [18 +/- 5% specific lysis at 25:1 effector:target (E/T) ratio] could be induced when HP CD3+ N901- cells were grown for 7 days in the presence of rIL-2 and PHA (0.5% v/v). Concomitantly, antigens N901 and H-25 were found to be coexpressed on a minor proportion (22 +/- 16 and 22 +/- 6%, respectively) of CD3+ (88 +/- 2% on day 7) cells. Four-week long-term culture of HP NK-depleted T cells in the presence of rIL-2 and PHA yielded a continuous increase in cytotoxicity against K562 cells (0 up to 46% specific lysis at 25:1 E/T ratio). Of particular interest was the emergence of cytotoxicity against the NK-resistant Daudi cell target (15 +/- 8% specific lysis at 25:1 E/T ratio on day 21). Expression of antigens N901 and H-25 as well as CD3 remained essentially unchanged in long-term culture. In sorting experiments, the H-25+ cell fraction was significantly enriched for cytotoxicity against K562, when compared to both H-25- and unseparated cell fractions. In summary, our results suggest that a proportion of HP CD3+ N901- T lymphocytes may give rise to cells that exhibit NK-like functional and phenotypic properties.     

Inhibition of swarming motility of Pseudomonas aeruginosa by branched-chain fatty acids.

Pseudomonas aeruginosa is capable of moving by swimming, swarming, and twitching motilities. In this study, we investigated the effects of fatty acids on Pseudomonas aeruginosa PAO1 motilities. A branched-chain fatty acid (BCFA)--12-methyltetradecanoic acid (anteiso-C15:0)--has slightly repressed flagella-driven swimming motility and completely inhibited a more complex type of surface motility, i.e. swarming, at a concentration of 10 microg mL(-1). In contrast, anteiso-C15:0 exhibited no effect on pili-mediated twitching motility. Other BCFAs and unsaturated fatty acids tested in this study showed similar inhibitory effects on swarming motility, although the level of inhibition differed between these fatty acids. These fatty acids caused no significant growth inhibition in liquid cultures. Straight-chain saturated fatty acids such as palmitic acid were less effective in swarming inhibition. The wetness of the PAO1 colony was significantly reduced by the addition of anteiso-C15:0; however, the production of rhamnolipids as a surface-active agent was not affected by the fatty acid. In addition to motility repression, anteiso-C15:0 caused 31% repression of biofilm formation by PAO1, suggesting that BCFA could affect the multiple cellular activities of Pseudomonas aeruginosa.     

Trypanosoma cruzi: a possible control of transfusion-induced Chagas' disease by phenolic antioxidants

The following phenolic antioxidant food additives were evaluated against Trypanosoma cruzi epimastigotes: BHT, BHA, gallic acid and its methyl, propyl, octyl, and lauryl esters, 2,4-di-tert-butyl-6-(4-methoxybenzyl)-phenol, 4,4'-isopropilidenediphenol, and protocatechuic acid and its ethyl ester. The inhibition of the respiration; the changes in motility, shape, and lysis of the parasites; and the human blood hemolysis caused by these chemicals were studied. Human blood samples experimentally contaminated with 2000 or 150,000 trypomastigotes per milliliter were freed of parasites after treatment for 24 hr at 4 degrees C with 5 or 10 mM BHT (2,6-di-tert-butyl-4-hydroxytoluene), respectively. Consequently, BHT and other phenolic compounds deserve further study to determine their role in preventing the transmission of Chagas' disease by blood transfusion.